Re: [PATCH] x86, x86_64: Fix checks for userspace address limit
From: Linus Torvalds
Date: Wed May 18 2011 - 06:09:24 EST
On Mon, May 16, 2011 at 4:42 AM, Ingo Molnar <mingo@xxxxxxx> wrote:
> Hm, something tickles me about this area that we would reintroduce a security
> hole, that we really wanted to treat the last page of user-space as some sort
> of guard page but i cannot quite remember it why ...
> IIRC Linus wrote bits of this so i'm Cc:-ing him just in case he remembers.
No, I suspect the patch is correct, and it's just a bug. I think it
comes from the "get_user_X()" cases that afaik use "jae" because they
add one less than the size (and thus avoid it entirely for the
single-byte case). See "getuser.S" in the same directory.
But right now I think I need to do a 2.6.39 release later today (after
I get some sleep), so doing it as a stable patch (presumably going
back to pretty much the beginning of time) is probably the right
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